This invention relates to the production of composite articles of cement or the like which are reinforced with an extended fibrillated net-shaped plastics material and to the articles so produced. According to the disclosed process objects consisting of a hydraulic binding material in which a reinforcing material is incorporated, are produced by forming a thin layer from an aqueous suspension of the hydraulic binding material and the reinforcing material, this layer being partly dewatered, rolled on a forming roller, removed from the forming roller once the desired thickness is obtained, shaped into its final form and then hardened.
As used in the present application the term hydraulically bound material means a composite of a binder and possibly various additives, which is hardened or bound by reaction with water. The starting material for the hydraulically bound material may be cement including calcium aluminium silicate cement, calcium oxide and silicondioxide, gypsum, all of the Portland cements of the various types, aluminous cements, puzzolanic cements (including cements derived from industrial slags), white cements, natural cements and in general all of the commercially available hydraulic cements.
Various reinforcing agents to these materials are well known. For instance the use of a reinforcement in the form of fibers, either synthetic or natural fibers, prepared with and mixed into hydraulically bound material is known. Also separate fibers may be incorporated in a criss-cross distribution throughout the article or in layers of separate fibers. A system where various fibers are incorporated into articles as a reinforcement in the form of a mat of fibers is also known. Additionally, reinforcement by means of incorporation of a plurality of layers of a net formed from a stretched and fibrillated plastics film is known as well. The product thus obtained is qualitatively better than one with fibers distributed criss-cross.
In a similar manner it is also known to continuously form articles with a fiber reinforcement made from hydraulically bound material, reinforced with separate fibers, in continuous processes. As an example there are the articles made of what is termed asbestos cement.
Prior to the process of the present invention it has not been possible to form on a continuous process basis relatively thin objects by the continuous application of a net fiber reinforcement such that the net reinforcement is present in a large number of layers.